[prasadw, pavani 960514 - later on that night :) ]

The problem was in the following statement in hasMoreElements:
while (--index >= 0 && (entry = table[index]) != null) ;
The "!= null" should be "== null" since the objective is to skip over the null
elements.


[prasadw, pavani 960514]

Here is a test program:

$ more T.java
import java.util.*;
import sun.misc.Cache;

class T {
    public static void main(String argv[]) {
        Cache numbers = new Cache();
        Enumeration enumElements;
        Enumeration enumKeys;
        Object object;

        numbers.put("one", new Integer(1));
        numbers.put("two", new Integer(1));
        numbers.put("three", new Integer(1));
        System.out.println("size = " + numbers.size());
        enumElements = numbers.elements();
        System.out.println("enumElements.hasMoreElements() = " +
            enumElements.hasMoreElements());
        enumKeys = numbers.keys();
        System.out.println("enumKeys.hasMoreElements() = " +
            enumKeys.hasMoreElements());
    }
}
$ javac T.java
$ java T
size = 3
enumElements.hasMoreElements() = false
enumKeys.hasMoreElements() = false


The problem is that when the hasMoreElements function in CacheEnumerator
is entered entry is not initialized.

/**
 * A Cache enumerator class. This class should remain opaque
 * to the client. It will use the Enumeration interface.
 */
class CacheEnumerator implements Enumeration {
    boolean keys;
    int index;
    CacheEntry table[];
    CacheEntry entry;

    CacheEnumerator (CacheEntry table[], boolean keys) {
        this.table = table;
        this.keys = keys;
        this.index = table.length;
    }
 
    public boolean hasMoreElements() {
        while (index >= 0) {
            while (entry != null)
                if (entry.check() != null)
                    return true;
                else
                    entry = entry.next;
            while (--index >= 0 && (entry = table[index]) != null) ;
        }
        return false;
    }

    public Object nextElement() {
        while (index >= 0) {
            if (entry == null)
                while (--index >= 0 && (entry = table[index]) == null) ;
            if (entry != null) {
                CacheEntry e = entry;
                entry = e.next;
                if (e.check() != null)
                    return keys ? e.key : e.check();
            }
        }
        throw new NoSuchElementException("CacheEnumerator");
    }

}

Changing the constructor as follows seems to fix the problem, though we
haven't tested it thoroughly. Also it would be helpful to comment on the
logic.

    CacheEnumerator (CacheEntry table[], boolean keys) {
        System.out.println("table.length = " + table.length);
        this.table = table;
        this.keys = keys;
        this.index = table.length - 1;
        this.entry = table[index];
    }